Haemophagocytic lymphohistiocytosis in X‐linked severe combined immunodeficiency

Haemophagocytic lymphohistiocytosis (HLH) is characterized by destruction of haematopoietic elements, and is associated with a variety of manifestations including immune abnormalities. We describe an infant with HLH who had no evidence of infection or malignancy. He had markedly reduced natural killer (NK) and T‐cell numbers and mitogen responses, consistent with severe combined immune deficiency. Western blot and flow cytometry analyses revealed an absence of interleukin (IL)‐2 receptor γ (γ common) chain expression and a transition (C → T) at nucleotide 684 in the γ common gene. This novel case highlights the need for a thorough evaluation of immunological phenotype and genotype in patients with HLH.